Flashcards in Integumentary System Deck (105)
The integumentary system includes:
1. Skin (cutaneous membrane)
2. Accessory structures (hair, oil & sweat glands, sensory receptors).
Approximate how thick is the skin?
Functions of integumentary system.
1. Regulates body temperature
2. Stores blood
3. Protection from external environment
4. Excretion and absorption
6. Vitamin D synthesis
Epidermis vs Dermis
-- more superficial, thinner
-- contains epithelial tissue
-- somewhat avascular
-- deeper and thicker
-- contains connective tissue
Not part of skin
Consists of areolar and adipose tissue
Functions: fat storage, blood vessel passage and location of pressure sensing nerve endings.
The epidermis is primarily composed of what tissue type?
Stratified squamous epithelium
4 principle cells of the epidermis
3 Langerhans cell
4 Merkel cells
90% of epidermal cells
Produce keratin and lamellae granules
Protein produced by keratinocytes
Protects skin and underlying tissue from heat, microbes and chemicals
Originate as tonofilaments which are converted by keratohyalin into keratin in the stratum granulosum.
Released by keratinocytes in stratum granulosum and stratum corneum
Produce water repellant sealant
Decreases entry of water and foreign materials (and water loss too).
Pigment produced by melanocytes and transferred to keratinocytes
Absorb damaging UV light
Shield nucleus of keratinocytes
AKA Intraepidermal Macrophage cells
Epidermal dendritic cells
Arise from RBM and migrate to epidermis.
Participate in immune responses against invading microbes. Antigen presenting.
AKA tactile epithelial cells
Least numerous epidermal cell
In deepest layer of epidermis.
Contact Merkel/tactile disc. Detect touch.
Five layers of the epidermis
1. Stratum basale/germinativum
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucidum (palms and soles)
5. Stratum corneum
AKA stratum germinativum
Deepest epidermal layer
SINGLE row of cuboidal or columnar keratinocytes
Also contain melanocytes, Merkel cells and stem cells (which produce keratinocytes)
If this layer is destroyed skin cannot regenerate
Cells attach to each other by desmosomes and to basement membrane by hemidesmosomes
8-10 cells layers held together by desmosomes
Second deepest layer or epidermis
Mostly keratinocytes but also Langerhans cells and melanocyte projections.
3-5 layers of flat cells undergoing apoptosis
Transition layer between deeper active strata and superficial dead cells.
Keratinocytes release lamellae granules.
Contain keratohyalin which converts tonofilaments into keratin
Layer of epidermis only found in finger tips, palms and soles of feet.
4-6 layers of flat dead cells.
Add additional toughness
25-30 layers of flat dead cells filled by keratin and surrounded by lipids
Most superficial layer of epidermis
Contain lamellar granules.
Protect against light, heat, chemicals and bacteria
Abnormal thickening of the stratum corneum of the epidermis due to friction.
Replacement of cell contents with keratin as cells move to skin surface
Takes 4-6 weeks.
Stem cells product keratinocytes.
Keratinocytes contain tonofilaments which are converted to keratin by keratohyalin in the stratum granulosum.
Epidermal growth factor (EGF) involved.
Dermis is composed primarily of what tissue type?
Dense irregular connective tissue containing collagen and elastin fibres
The Dermis contains:
Fibres (collagen and elastin)
Cells (fibroblasts, macrophages, fat cells)
Hair follicles, glands, nerves and blood vessels.
Ability to return back to the original shape
Ability to stretch
Ability to resist pulling or stretching.
Two major regions of the dermis
Papillary and reticular
Top 20% of dermis
Thin collagen and elastic fibres
Has dermal papillae (epidermal ridges)